Known is a control system like one in a bipedal walking robot, for controlling actuators provided at hip joints, knee joints, and foot joints of its legs, shoulder joints, elbow joints and wrist joints of its arms, and the like.
In the control system, the actuators are driven and controlled based on a communication of a control signal between a main control unit and each sub control unit through a signal line. Further, from a viewpoint of appropriate drive and control, it is judged whether a state of the communication is normal or abnormal in the process described below, before driving the robot.
First of all, power is supplied to each of the sub control units from a control system power source through a control system power line. Next, an ID request signal is transmitted from the main control unit to each of the sub control units through a signal line. Each of the sub control units receives the ID request signal and then transmits an ID signal to the main control unit through the signal line as above. This ID signal corresponds to an ID which has been assigned to each of the sub control units in advance. Accordingly, the main control unit identifies which one of the sub control units corresponds to which one of the actuators.
Thereafter, a test signal is transmitted from the main control unit to each of the sub control units through the signal line. Each of the sub control units receives the test signal, inverts bits of the test signal, and then transmits this signal back to the main control unit as a response signal. Based on whether or not the response signal is a signal which is obtained by accurately inverting the bits of the previously transmitted test signal, the main control unit judges whether the communication state with each of the sub control units is normal or abnormal.
When the main control unit judges that the communication state with each of the sub control units is normal, power is supplied to each of the sub control units from a drive system power source through a drive system power line. Based on the communications of the control signals with the main control unit through the signal lines, the sub control units control power supply from the drive system power source to the actuators. Therefore, the actuators are driven and controlled, and the right and left legs and arms of the robot are thus driven, allowing the robot to realize a walking function and the like.
Meanwhile, from a viewpoint of ensuring easy movement of a joint area of the robot, the signal line and the power line are provided to be close to each other especially at a joint portion. In the vicinities of the hip joints and the shoulder joints in particular, the signal lines and the power lines extending to the knee joints and the elbow joints, which are respectively provided down from the hip and shoulder joints, are concentrated. Hence, the communication state which was normal before driving the robot may become abnormal after the robot is driven, owing to an influence of a noise generated from the close drive system power line. This may cause abnormal drive and control of the actuator.
However, in the aforementioned method, whether the communication state is normal or abnormal is judged while power is supplied neither to the sub control units nor to the actuators from the drive system power source. Thus, this method is not capable of eliminating a possibility that the communication state which was normal before driving the robot becomes abnormal after the robot is driven, thereby causing the abnormal drive and control of the actuator.
Thus, in the present invention, a problem to be solved is to provide a method in which communication between a main control unit and each sub control unit can be judged to be normal or abnormal, in a condition where a noise may be generated from the drive system power line.